ESR N° 5: Monitoring spatio-temporal water redistribution in the subsurface with seismic methods

Research Fellow: Lara Blazevic

Profile
Profile

hosted by University of Rennes 1 & Sorbonne University

Supervisors
Laurent Longuevergne
Ludovic Bodet
Damien Jougnot

Secondments
University of Lausanne – 6 months (15/04/19-15/08/19 and 01/02/20-01/04/20)

Research objectives

  • Qualify seismic methods as tools to capture temporal evolution of the subsurface water content/saturation.
  • Synthetize and propose links between porosity, saturation/pressures states, hydrodynamic parameters and seismic properties in both consolidated and unconsolidated media.
  • Set up experiments to evaluate petrophysics/rock physics relationships and relate the available geophysical information to subsurface properties.
  • Gain insights on the challenges related to the application of these methods in industry.

Project description

Geophysical methods are widely used in hydrological contexts as they can provide a non-intrusive way to obtain subsurface information. Electrical methods are conventionally employed to derive water content and fluxes, however, seismic methods have been recently used to study temporal variations related to these properties. As the interest for understanding vadose zone processes increases due to their importance for agriculture andpollutants transport, and as time-lapse approaches develop, we investigate the applicability of these techniques in field contexts.

Seismic prospecting techniques are commonly used at different scales in hydrogeophysics. Nevertheless, seismic imaging remains mainly confined tothe characterization of geological structures than used to constrain hydrological models. The seismic signal is by definition related to mechanical properties that partly depend on material’s composition, porosity, state of stress, and degree of saturation. The behavior of pressure (P-) and shear (S-) waves in the presence of fluid is partially decoupled. The use of VP/VS ratio, or the pseudo-Poisson’s ratio, to estimate fluid saturation in rocks is well known in e.g. oil and gas applications, however it remains underused in near surface applications.

By using time-lapse approaches and coupling seismic with hydrogeological and mechanical properties, we aim at developing a fully integrated approach that can result in more quantitative studies of hydrological processes in the subsurface.

Tasks & methodology

  1. Find appropriate links between hydrodynamic parameters and seismic properties.
  2. Exploit the full wealth of active seismic signals and extract information from temporal variations.
  3. Carry out controlled infiltration experiments in the field while acquiring seismic and electrical resistivity data to better link hydrodynamic processes to geophysical responses.
  4. Test different geophysical inversion techniques to get greater insight into the hydrogeological characteristics of the vadose zone.

Data & Datasets

Data acquired during the research project will be inserted in the H+ database.

Dissemination and communication

Blazevic, L., Bodet, L., Longuevergne, L., Pasquet, S., Jougnot, D. (2019) Hydrogeophysical Monitoring of a Controlled Infiltration Experiment at the Ploemeur Hydrological Observatory. H+ Network Meeting, Paris, June 3-4 (Oral presentation).

Blazevic, L., Bodet, L., Jougnot, D., Longuevergne, L. (2018) Finding appropriate rocks physics models to interpret seismic data in hydrogeophysics applications. American Geophysical Union Fall Meeting, Washington, December 10-14 (Poster).

4th Cargèse Summer School (2018), poster : “Monitoring spatio-temporal water redistribution in the subsurface with seismic methods” and video below

Poster Presentation of Lara during the Cargèse Summer School
  • Oral presentation at doctoral school days at MINES ParisTech:
    • 19/03/2019 Paris: Journées des Doctorants – École Doctorale Géosciences, Ressources Naturelles et Environnement (poster)
    • 05/04/2018 Paris: Journées des Doctorants – École Doctorale Géosciences, Ressources Naturelles et Environnement (oral presentation)
Presentation of Lara’s experiment at Ploemeur Hydrological Observatory